1. Field of the Invention
The present invention relates to lighting systems and, more specifically, to an optical element and a lamp assembly using the same. The assembly according to the present invention will find utility in vehicle lighting systems, as well as in a variety of non-automotive illumination applications.
2. Description of the Related Art
Conventional automotive lighting systems, such as head lamps, tail lamps, signal lamps and interior lamps, typically are constructed as bulb and reflector systems. In such a system, the filament of the bulb emits the light utilized by the system and the filament is located at or near a focal point of a parabolic reflector. The light is collected by the reflector and reflected in the desired direction as a light beam. If necessary, a lens is used to shape the light beam into the specific pattern required by the particular application of the lighting system itself.
While widespread in use, bulb and reflector systems are well known as having various disadvantages. One such disadvantage is the longevity of the filament in the bulb. This useful life is approximately one third that of other light sources, such as LED light sources. Another disadvantage of a filament bulb and reflector system is that only about 30% of the light emitted from the bulb""s filament is converted into useful light. Yet another disadvantage is that bulb and reflector systems have significant packaging requirements (having a sizable depth measured along its focal axis and a height/width measured in directions perpendicular to the focal axis) thereby limiting exterior aerodynamics, aesthetic styling and engine bay space. Finally, the energy consumption of reflector system is relatively high with a significant amount of the energy being consumed as thermal radiation, not emitted as useful light. In view of the amount of thermal radiation emitted by bulbs and reflector systems, design and construction of the reflector and associated housing materials become important factors and can significantly affect the cost of the overall system.
In an effort to move away from bulb and reflector lighting systems, various other approaches have been proposed. One such approach utilizes a fiberoptic light guide which transmits light from a remote source to a reflector. Problems with these systems include the further use of reflectors in combination with a high intensity discharge source. Limitations also exist on the light guides relating to transmission capacity and the degrading effects of environmental factors.
Another system proposed as an alternative to the bulb and reflector systems is one where a laser operates as the light source. While some of these systems appear promising, problems include variation in illumination intensity across the width of the laser light beam, as well as designing criteria so as to avoid the formation of hot spots when the laser light beam is transmitted.
In view of the above and other limitations on the known technologies, it is apparent that there exists a need for an improved lighting system which overcomes the various and other disadvantages of the above and other lighting systems.
The present invention achieves the above and other objectives by providing a lamp assembly that includes a plurality of light sources utilized in conjunction, preferably, with an equal plurality of optical elements. The optical elements themselves may be formed into a light transmitting manifold. Each optical element includes a top surface, a bottom surface, sides, and a plurality of facets. The facets are oriented to receive light from the light sources through the front surface and reflect light through the top surface. The manifold includes a composite top surface, a composite bottom surface and a composite perimeter surface, respectively defined by the top surfaces, bottom surfaces and front surfaces of the optical elements. Preferably the facets are formed in the bottom surface and, in order to shape the light transmitted from the manifold, an optic component may be provided on the top surface and/or the bottom surface of the optical elements.
While the manifold is preferably manufactured with a unitary construction, with each optical element identifiable as a portion thereof, the manifold may also be formed by orienting discrete optical elements relative to one another and attaching the optical elements to one another along their sides or other areas. Attachment may be by bonding or other means.
In one preferred embodiment, substantially all of the optical elements have a common shape. Preferably, the common shape is a pie wedge shape. In another embodiment, the common shape is a bar shape. The pie wedge shape may be such that the sides utilized in defining the pie wedge shape are of equal length. In another alternative embodiment, the sides are of an unequal length.
In another aspect, the invention may be seen as a manifold defined by a plurality of optical elements. The manifold may be unitarily formed or formed out of discrete optical elements joined together with one another by various means. The optical elements themselves include a top surface, a bottom surface, a front surface and sides. The optical elements are additionally provided with reflective facets that are oriented such that they receive light through the front surface and reflect light through the top surface of the optical element. As is seen from the detailed discussion that follows, a plurality of reflective facets are provided in each optical element. Preferably, the reflective facets are provided in the bottom surface of the optical element. When provided with a plurality of reflective facets in the bottom surfaces of the optical elements, the bottom surfaces can generally be viewed as having a stepped construction.
In a preferred construction, the optical elements defining the manifold exhibit a common shape. The shape, when viewed in the direction toward the top surface, is a pie wedge (tapered) shape. The sides of the pie wedge shape may be equal in length, thereby giving the pie wedge shape an equilateral construction or, alternatively, the sides may be unequal in length.
If desired, optic components can be provided on the top surface and/or bottom surface of the optical elements to shape the light being emitted from the optical element. When provided on the bottom surface, the optic components may replace one or more of the reflective facets.
In a further aspect, the present invention can be viewed solely as a light transmitting optical element having the characteristics and features described above in connection with the manifold.
Additional objects, advantages and features of the present invention will be readily appreciated by those skilled in the art upon review of the following detailed description, taken in conjunction with the drawings and the appended claims.